Can two people with the same blood type have a child with a different blood type?

Yes it could. For example if both parents are a+, children could be a+, a-, o+, o-.
No. I suppose you can have one through adoption or donated ivf but otherwise this doesn't happen.(this doesn't apply to the rh factor issue which is inherited separately from type).
Yes. If parents are a or b, it is possible for the baby to be o. This is because there are two genes for each parents. So a parent could be bb or bo for example. This means that if a parent is ao and one is bo the child could be o as it takes one gene from each parent. Hope this helps.